U.S. patent number 8,838,228 [Application Number 13/228,592] was granted by the patent office on 2014-09-16 for systems and methods for reducing the proliferation of microorganisms.
The grantee listed for this patent is Arthur Beisang, III, Andrew Kirchoff, David Shelander. Invention is credited to Arthur Beisang, III, Andrew Kirchoff, David Shelander.
United States Patent |
8,838,228 |
Beisang, III , et
al. |
September 16, 2014 |
Systems and methods for reducing the proliferation of
microorganisms
Abstract
Systems and methods are provided that reduce the likelihood of
infection caused by microorganisms. In general, microorganism
population control can be achieved by exposing the population to an
effective dose of electromagnetic radiation sufficient to cause a
reduction in proliferation of the microorganism, wherein the
electromagnetic radiation has a center wavelength between about 385
nm and about 425 nm. In preferred embodiments, the systems and
methods described herein can be embodied in catheterization
systems.
Inventors: |
Beisang, III; Arthur (North
Oaks, MN), Kirchoff; Andrew (White Bear Lake, MN),
Shelander; David (Roseville, MN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Beisang, III; Arthur
Kirchoff; Andrew
Shelander; David |
North Oaks
White Bear Lake
Roseville |
MN
MN
MN |
US
US
US |
|
|
Family
ID: |
47006944 |
Appl.
No.: |
13/228,592 |
Filed: |
September 9, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20120265120 A1 |
Oct 18, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61476190 |
Apr 15, 2011 |
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Current U.S.
Class: |
604/20 |
Current CPC
Class: |
A61N
5/0624 (20130101); A61N 5/0616 (20130101); A61N
2005/0643 (20130101); A61N 2005/0662 (20130101) |
Current International
Class: |
A61N
1/30 (20060101) |
Field of
Search: |
;604/20 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sirmons; Kevin C
Assistant Examiner: Hall; Deanna K
Attorney, Agent or Firm: Underwood & Associates, LLC
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority under 35 U.S.C. .sctn.119(e) of
U.S. Patent Application No. (USPN) 61/476,190, filed Apr. 15, 2011
by Arthur Allen Beisang, David John Shelander, and Andrew John
Kirchoff, entitled "Method and Apparatus for Sterilizing or
Disinfecting Mammalian Tissues and Catheters Using Wavelengths of
Light in the Violet Range." USPN 61/476,190 is hereby incorporated
by reference in its entirety as if fully set forth herein.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
None.
Claims
What is claimed is:
1. A system for reducing the likelihood of infection in a living
system, comprising: a solid-state light source configured to
produce an effective dose of electromagnetic radiation in the
violet portion of the electromagnetic spectrum so as to reduce the
proliferation of microorganisms on a target surface, wherein said
effective dose of electromagnetic radiation is delivered to said
target surface via an optical fiber in optical communication with
said light source; and an electronic control module configured to
allow a user to toggle emission of said effective dose between on
and off states.
2. The system of claim 1, wherein said microorganisms are one or
more of: bacteria, fungi, or protist.
3. The system of claim 1, further comprising: a support body
capable of securing a distal end of said optical fiber proximate to
said target surface in an orientation suitable to project said
electromagnetic radiation onto said target surface.
4. The system of claim 3, wherein said target surface is a selected
portion of skin, tissue, bone, muscle fiber, lumen, or organ.
5. The system of claim 1, wherein said solid-state light source is
configured for producing said effective dose of electromagnetic
radiation such that it is capable of transmission through a
protective dressing comprising polyurethane and onto said target
surface while minimizing the likelihood of causing damage to cells
of said target surface.
6. The system of claim 5, wherein said dressing comprises one or
more layers of a solid, liquid, or gel material that is at least
partially transmissive with respect to said electromagnetic
radiation and formulated to provide a therapeutic effect to said
target surface.
7. A system for reducing the likelihood of infection at or near a
catheterization site, comprising: a solid-state light source
capable of producing an effective dose of electromagnetic radiation
sufficient to reduce proliferation of a population of infectious
microorganisms, wherein said electromagnetic radiation has a center
wavelength between about 385 nm and about 425 nm; and a catheter at
least partially engaged with at least one optical fiber configured
to transmit said effective dose of electromagnetic radiation from a
proximal end of said waveguide to a distal end of said waveguide,
wherein said distal end of said waveguide is capable of projecting
said radiation onto a target surface at or near said
catheterization site.
8. The system of claim 7, wherein said optical fiber is at least
partially embedded in said catheter.
9. The system of claim 8, wherein said elongate catheter is capable
of transporting fluids into and out of an animal body.
10. The system of claim 7, wherein said system is configured such
that said effective dose is capable of being transmitted through a
protective dressing formed primarily of polyurethane.
11. The system of claim 10, wherein said protective dressing
comprises a compound formulated to prevent infections in
animals.
12. The system of claim 7, further comprising an electronic control
module configured to allow user input for controlling at least one
of: exposure time, exposure intensity, and time between repeated
exposures of said electromagnetic radiation onto said catheter
insertion site.
13. A method for reducing the likelihood of infection in a living
system, comprising: providing a light source capable of producing
an effective dose of electromagnetic radiation sufficient to cause
a reduction in proliferation of a microorganism and having a center
wavelength between about 385 nm and about 425 nm; and providing an
elongate catheter, comprising: a housing having a bore extending
therethrough from a proximal catheter end to a distal catheter end,
an elongate lumen in fluid communication with said bore extending
from said proximal catheter end and configured to be inserted into
tissue of an animal body at a catheter insertion site; and one or
more optical fibers at least partially engaged with said elongate
catheter, wherein a distal end of said waveguide is configured to
receive said electromagnetic radiation, and a proximal end of said
waveguide is configured to project said electromagnetic radiation
about said catheter insertion site to cause necrosis in said
infectious microorganism.
14. The method of claim 13, wherein said light source comprises a
laser, diode, excitable gas, or filament.
15. The method of claim 13, wherein said distal end of said
waveguide is configured to project said effective dose within a
tissue or organ of said living system.
16. The method of claim 13, further comprising providing a
therapeutic dressing that is substantially transparent to said
electromagnetic radiation and configured to fix said proximal
catheter end proximal to said catheter insertion site.
17. The method of claim 13, wherein said light source is configured
to provide controllable effective doses of said electromagnetic
radiation for a selected exposure period over a selected period of
time to said catheter insertion site.
18. The method of claim 13, wherein said effective dose is
determined based on the type of said infectious microorganism(s)
capable of causing said infection.
Description
TECHNICAL FIELD
This disclosure relates to systems and methods for reducing the
likelihood of infections caused by microorganisms. In particular,
this disclosure relates to systems, articles, and methods for
reducing the likelihood of nosocomial infections using an effective
dose of electromagnetic radiation in a preferred range of
predominant (center) wavelengths.
BACKGROUND
Infection is a primary concern in healthcare settings. Nosocomial
infections are infections that originate in a hospital or a
healthcare service unit, often the result of infectious
microorganisms entering the body through open wounds, skin lesions
or incisions, or mucous membranes. Microorganisms including harmful
bacteria can cause infections in the body when they traverse the
protective layers of the skin. There can be increased
susceptibility to infection where skin ulceration exists or where
the dermal layers are breached, such as catheter insertion sites in
skin. When infections occur, they can cause significant morbidity
and mortality thus increasing both the cost of healthcare and the
length of hospitalization.
Catheters are placed into the body for many reasons. It is well
known in the medical arts that the skin or other entrance points
must be thoroughly disinfected prior to the introduction of any
catheter, e.g., through the skin. It is also common practice to
place a sterile, adhesive flexible membrane over the catheter
insertion site to further protect against microorganism infection
at the catheter entry site. It can be difficult, however, to
maintain sterility at catheter insertion sites over a length of
time. Despite ongoing infection prevention and intervention
measures, nosocomial infections originating from catheterization
procedures remain a serious healthcare problem.
Some infection prevention measures include completely changing the
overlying catheter dressings and disinfecting the insertion site
with chemical disinfectants or sterilizing agents. These procedures
can increase the chances of dislodging the underlying catheter,
however, and can additionally cause harm to the skin and blood
vessels. Furthermore yet, some patients react unfavorably to
chemical disinfectants through allergic reactions or
irritation.
SUMMARY
In one general aspect, a system for reducing the likelihood of
infection in a living system is provided. The system includes a
light source capable of producing an effective dose of
electromagnetic radiation so as to reduce the proliferation of
microorganisms on a target surface, where the electromagnetic
radiation has a center wavelength between about 385 nm and about
425 nm. The system further includes a protective dressing
configured to cover all, or a portion of the target surface, where
the dressing includes a window that is substantially transparent to
the electromagnetic radiation.
In one embodiment, the microorganisms are one or more of: bacteria,
fungi, or protist.
In one embodiment, the system further includes a support body
capable of securing the light source proximate to the target
surface in an orientation suitable to project the electromagnetic
radiation through the dressing and onto the target surface. In one
embodiment, the target surface is a selected portion of skin,
tissue, bone, muscle fiber, lumen, or organ.
In one embodiment, the protective covering includes a clear acrylic
substrate and an adhesive layer configured to adhere the protective
covering to the target surface.
In one embodiment, the dressing includes one or more layers of a
solid, liquid, or gel material.
In one general aspect, a system for reducing the likelihood of
infection caused by catheterization is provided. The system
includes a light source capable of producing an effective dose of
electromagnetic radiation sufficient to reduce proliferation of a
population of infectious microorganisms, where the electromagnetic
radiation has a center wavelength between about 385 nm and about
425 nm. The system further includes optical components and support
structures for projecting the electromagnetic radiation onto, and
adjacent a catheter insertion site, where a catheter is inserted
into a body part of a living system.
In one embodiment, the means for projecting the radiation onto, and
adjacent the incision site includes one or more waveguides
configured to carry the electromagnetic radiation from a distal end
to a proximal end of the catheter. The distal end of the waveguide
is configured to receive the output of the light source, and the
proximal end is configured to project the electromagnetic radiation
onto the incision site.
In one embodiment, the waveguide is embedded in a catheter having a
central bore for transporting fluids into and out of the living
system.
In one embodiment, the system further includes a protective
dressing configured to reversibly hold the projecting means
proximate to the catheter insertion site.
In one embodiment, the protective dressing is one or more of a
solid, liquid, or gel dressing.
In one embodiment, the system further includes a control module
configured to allow user input for controlling one or more of
exposure time, exposure intensity, and time between repeated
exposures of the electromagnetic radiation.
In one general aspect, a method for reducing the likelihood of
infection in a living system is provided. The method includes
providing a light source capable of producing an effective dose of
electromagnetic radiation sufficient to cause a reduction in
proliferation of a microorganism. The light source has a center
wavelength between about 385 nm and about 425 nm. The method
further includes providing a dressing for covering an exposure area
that is susceptible to infection through the presence of the
microorganisms. The method further includes projecting the
electromagnetic radiation through the dressing, and onto the
exposure area in an effective dose sufficient to reduce the
proliferation of the microorganisms.
In one embodiment, the light source includes a laser, diode,
excitable gas, or filament.
In one embodiment, the exposure area is a catheter insertion site,
where a catheter has been introduced into the living system. In one
embodiment, the exposure area includes skin of the living
system.
In one embodiment, the dressing is one or more of a solid, liquid
or gel dressing that is substantially transparent to the
electromagnetic radiation.
In one embodiment, projecting the electromagnetic radiation through
the dressing includes projecting the output of the light source
toward the dressing; or carrying the output of the light source to
an area proximate to the exposure area through the use of one or
more waveguides, and directing an output end of the waveguide onto
the dressing so as to irradiate the exposure area with the
electromagnetic radiation.
In one embodiment, the exposure area receives a plurality of
effective doses over a selected period of time to further prevent
colonization of the microorganisms.
In one embodiment, the effective dose is determined based on the
type of microorganism(s) on or near the exposure area.
Certain advantages of the systems and methods described herein
include: a non-invasive treatment method for reducing the
likelihood of nosocomial and other infections; reduction of
undesirable microorganism population in and around a catheter
insertion site without the use of sterilizing agents and other
chemicals, or ultra-violet radiation, which has been shown to cause
skin cancer; a catheterization system that does not require
frequent dressing changes; and the ability to protect against
infection from different types of undesirable microorganism
populations with a single system; among others.
Unless otherwise defined, all technical and scientific terms used
herein have the same meaning as commonly understood by one of
ordinary skill in the art. Although methods and materials similar
or equivalent to those described herein can be used in the practice
or testing of any described embodiment, suitable methods and
materials are described below. In addition, the materials, methods,
and examples are illustrative only and not intended to be limiting.
In case of conflict with terms used in the art, the present
specification, including definitions, will control.
The foregoing summary is illustrative only and is not intended to
be in any way limiting. In addition to the illustrative aspects,
embodiments, and features described above, further aspects,
embodiments, and features will become apparent by reference to the
drawings and the following detailed description and claims.
DESCRIPTION OF DRAWINGS
The present embodiments are illustrated by way of the figures of
the accompanying drawings in which like references indicate similar
elements, and in which:
FIG. 1 shows a system for reducing the likelihood of infection,
according to one embodiment;
FIG. 2 shows a system for reducing the likelihood of infection,
according to one embodiment.
FIG. 3A shows a system for reducing the likelihood of infection,
according to one embodiment;
FIG. 3B shows an alternative arrangement of the system shown in
FIG. 3A, according to one embodiment;
FIG. 4 shows a system for reducing the likelihood of infection at
or near a catheter insertion site, according to one embodiment;
FIG. 5 shows a system for reducing the likelihood of infection at
or near a catheter insertion site, according to one embodiment;
FIG. 5A shows a cross-sectional view of a terminal end of the
catheter 543 described with respect to FIG. 5, according to one
embodiment;
FIG. 6 shows a catheterization system, according to one
embodiment;
FIG. 6A shows a cross-sectional view of a terminal end of the
catheter housing 601 described with respect to FIG. 6;
FIG. 7 shows a system for reducing the likelihood of microorganism
growth, according to one embodiment;
FIG. 8 shows steps of a method for reducing the likelihood of
microorganism growth on a target surface, according to one
embodiment; and
FIG. 9 shows steps of a method for reducing the likelihood of
microorganism growth on a target surface, according to one
embodiment.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
In general, systems, articles, and methods are disclosed for
reducing the likelihood of infection resulting from undesirable
microorganism growth in, or on living systems, or on equipment that
comes into contact with living systems. The term "microorganism,"
as used herein, generally refers to microscopic organisms such as
bacteria, fungi, protists, and other microorganisms capable of
multiplying or colonizing to cause an infection in a host. It will
be understood, however, that the systems and methods described
herein for reducing the likelihood of infection from these
organisms can also be applied for controlling, preventing, or
reducing the likelihood of infections from viruses. "Microorganism
growth," as used herein, generally refers to an increase in a
population of microorganisms.
Nosocomial infections (infections originating in a hospital) are an
increasing primary care concern because of the risk of further
illness to the patient. The likelihood of developing an infectious
disease generally increases when a pathogen enters a body through
mucous membranes, inhalation, or when skin is pierced, often times
providing a direct route for pathogens to enter the blood stream.
In many living systems, the skin is a primary barrier for
preventing infection and disease by foreign substances.
Catheters are used in hospitals, ambulances, triage units, and even
in battlefields as a way to rapidly introduce fluids, medicines,
and other agents directly into a patient's bloodstream or other
parts of the body. Catheters are often used in providing
intravenous (IV) therapy to patients by accessing veins and
arteries in the arms and legs, for example. In many cases, the
benefits of this direct access into the body outweigh certain
health risks, which include, among others, risk of infection. Even
when proper sterilization techniques are performed prior to
insertion of a catheter, there is a risk of microorganism growth in
the insertion area which provides a direct route for infectious
agents to enter the body.
In one general aspect, the likelihood of microorganism growth can
be reduced around a catheter insertion site by irradiating the area
with electromagnetic radiation, i.e., light, having a center
wavelength between about 385 nanometers (nm) and about 425 nm. As
used herein, the term "center wavelength" refers to a peak emission
wavelength of a given color of light. For example, some laser light
has a bandwidth that includes wavelengths of light on low- or
high-energy sides (i.e., red-shifted or blue-shifted, respectively)
of the predominant color of the light.
Referring now to FIG. 1, a system 100 for reducing the likelihood
of infection is shown, according to one embodiment. In this
embodiment, a patient's left arm 105 is shown; inserted into the
arm 105 is a catheter 130. The portion of the catheter 130 shown as
a solid line in FIG. 1 exists outside of the arm, while the dashed
portion indicates the portion of the catheter within the body,
i.e., under the skin 160. The catheter 130 is shown inserted
through an insertion site 150 in the arm 105 which can be, e.g., an
incision or a break in the skin's continuity from insertion of a
needle, and a dressing 120 is shown covering both the insertion
site 150 and a portion of the exterior-exposed catheter.
The dressing 120 can be any type of bandage, adhesive, or covering
used for reducing the risk of infection in patients. Common
dressings for this purpose include, not by way of limitation,
absorbent acrylic, hydrocolloid, hydrogel, foam, transparent films,
and composites, among others. Those skilled in the art will
appreciate that hospitals, health care clinics, ambulance services,
and other health care providers often use a wide array of dressings
for this particular purpose. In one preferred embodiment, the
dressing 120 is an absorbent clear acrylic dressing sold under the
Tegaderm brand, produced by 3M Skin and Wound Care Division, 3M
Corporation, St. Paul, Minn., USA. Such a dressing usually includes
a transparent or translucent sheet of acrylic with an adhesive ring
disposed about the periphery of the sheet that adheres to the
patient's skin to keep the dressing in place. The transparent or
translucent sheet allows heath care providers to monitor a catheter
while minimizing the disturbance that can otherwise be caused by
frequent dressing changes. In another preferred embodiment, the
dressing 120 includes a substantially sterile transparent or
semi-transparent film configured to reduce or prevent the
introduction of microorganisms to the insertion site 150. An
integral adhesive can surround the film about its periphery to
adhere the film to the patient's skin. One exemplary dressing of
this type is sold under the Sorbaview brand by Centurion Medical
Products Corporation, Williamston, Mich., United States.
The catheter 130 can be any type of tube, lumen, or cannula used
for introducing substances to, or removing fluids or other
substances from a body. Exemplary catheters include those used for
intravenous therapy, and those configured to be inserted into a
body cavity, duct, or vessel to allow drainage (e.g., in the case
of a urinary catheter), to administer fluids, or provide access by
surgical instruments to internal body parts e.g., in the practice
of angioplasty or endoscopy. The catheter 130 can be a temporary
catheter, i.e., an "indwelling" catheter or a permanent catheter
generally referred to as a "permcath" and may be flexible or rigid
depending on the needs of the patient and the treatment plan of the
caregiver.
In this embodiment and all other embodiments described herein, the
likelihood of developing an infection as a result of
catheterization can be reduced by irradiating the insertion site
150 and the surrounding area with an effective dose of light having
a center wavelength of between about 385 nm and about 425 nm, e.g.,
light having a center wavelength of 385 nm, 390 nm, 395 nm, 400 nm,
401 nm, 402 nm, 403 nm, 404 nm, 405 nm, 406 nm, 407 nm, 408 nm, 409
nm, 410 nm, 415 nm, 420 nm, or 425 nm. In general, and without
wishing to be bound by theory, it is believed that an effective
dose of light in the wavelength range of between about 385 nm and
about 425 nm (hereinafter referred to as "violet" light) causes
either microorganism death, or a disruption in microorganism
reproduction, or both, and thus can be used as an "antimicrobial"
agent, in the sense that it can reduce proliferation of
microorganisms.
In preferred embodiments, the light source 110 is capable of
emitting light with a center wavelength of about 405 nm. Exemplary
light sources 110 for this purpose include, not by way of
limitation, lasers, diodes, excitable gases or filaments, and other
light sources. In this and all other embodiments, the light source
110 can be configured, including using lenses, windows, filters,
and any optics necessary, so as to deliver violet light to a
selected treatment area in an effective dose capable of reducing or
preventing the proliferation of microorganisms.
In one embodiment, a light source 110 capable of producing or
transmitting light radiation (indicated by reference numeral 140 in
FIG. 1) in the aforedescribed wavelength range can be positioned a
selected distance from the surface of the arm (i.e., the skin 160)
so as to irradiate a desired area around the catheter insertion
site 150 in an effective dose as shown in FIG. 1.
In general, the skin 160 surrounding the insertion site 150 can be
exposed for a selected length of time. The exposure time can be
controlled using a timer, for example, through the use of an
electronic control module or other methods. In another embodiment,
the exposure time can be controlled manually, e.g., through use of
a switch, button, or other control that allows a caregiver to
irradiate the target area for a selected amount of time.
In general, the area of the skin exposed to the radiation 140 can
be chosen according to the type of catheter used, as well as the
type of dressing used (if any), the presence of open sores,
lesions, or other breaches of the skin (if any), and other
considerations that can be determined by the user of the system 100
(e.g., a healthcare worker). For example, in the case of a single
intravenous catheter, prepared under relatively sterile conditions
and placed by an experienced medical provider, the caregiver may
decide to irradiate a small area (e.g., 3-4 cm) around the
insertion site to prevent the likelihood of infectious
microorganism growth in that area. In another example having
somewhat opposite circumstances, a patient may be delivered to a
hospital after an automobile accident, where paramedics emergently
inserted an intravenous catheter to reduce the likelihood of shock.
In this case, where thorough sterilization techniques may have been
secondary to stabilizing the victim, the irradiation area of the
skin around the catheter insertion site 150 can be enlarged to
encompass a greater area, e.g., 10-12 cm around the insertion site
150. Furthermore, in the latter case, the exposure time can be
increased a desired amount to account for the increased risk of
infection under the circumstances described.
In some embodiments, the light source 110 can be mounted in a
preferred configuration and orientation so as to provide an
effective dose of radiation to the treatment area. For example, the
light source 110 can be mounted a selected distance from the
patient's skin so as to provide reproducible exposure to a desired
area of the body, e.g., a catheter insertion site. One suitable
approach for this purpose includes using molded plastic components
that attach to a body part (e.g., attach to an arm using a strap),
while simultaneously providing a bridge or other frame component
configured to secure the light source 110 in a preferred
configuration to irradiate selected area(s) of the patient's skin.
In another embodiment, the light source can be attached directly to
the dressing in a configuration that directs the emitted light 140
toward the target area. In one example of such an embodiment, an
array of LED lights capable of providing an effective dose of
violet light to cause reduction in proliferation of microorganisms
can be integrated into one side of a dressing using glues,
adhesives, hook-and-loop fastening systems, cloths, or other
methods that will be apparent to skilled artisans.
Referring now to FIG. 2, a system for reducing the likelihood of
infection is shown, according to one embodiment. This system,
similar to the system shown and described with respect to FIG. 1,
includes a light source 210 capable of producing an effective dose
of violet light to reduce the likelihood of microorganism
proliferation on a target area of the skin 240. A catheter 230 is
shown inserted into the skin 240, where the dashed lined indicates
the portion of the catheter under the skin layers.
The blow up region shows a dressing 235 having a plurality of
layers, 250, 251, and 252 which can be the same or different
materials. In one example, one of the layers (e.g., layer 250) is
an acrylic sheet that is transparent to violet light; one of the
layers (e.g., layer 251) includes a cotton or other absorbent
material; and one of the layers, (e.g., layer 252) includes a gel
layer. In this example, the light rays 214 can propagate through
the layers to reach the skin layer 240 in an effective dose to
reduce or prevent proliferation of microorganisms. It will be
understood that the dressing 235 can include one or more layers of
material as necessary to provide a desired treatment for the
patient. For example, a burn victim may benefit from a dressing
having a silver-containing gel layer in contact with their skin
(e.g., layer 252) which covers the inserted catheter 230.
Referring now to FIG. 3A, one embodiment of a system 300 for
reducing the likelihood of infection is shown. Similar to the
embodiment of FIG. 1, FIG. 3 shows a catheter 330 inserted into the
skin 380 of a patient's arm 305 through an insertion site 350
(e.g., an incision in the skin produced by an IV needle). The
insertion site 350 and surrounding area is covered by a dressing
320 that is at least partially transmissive with respect to violet
light. In a preferred embodiment, the dressing 320 is an absorbent
clear acrylic dressing sold under the Tegaderm brand (vide
supra).
In this and other embodiments, violet light can be generated
remotely by a light source 310, which can be a laser, diode, or
other light source capable of producing an effective dose of violet
light at the treatment site. The violet light can be carried by a
waveguide 360, e.g., a fiber optic cable, to a dispersion optic 395
capable of dispersing the light from the fiber optic onto a desired
area. It will be understood that the term "dispersion" as used
herein, refers to increasing the irradiance area of the light from
a source to a target, e.g., from the output end of a waveguide to a
larger area on a patient's skin; the term does refer to the spatial
or temporal separation of light into components of different
wavelengths.
The dispersion optic 395 can be, in one example, a lens that causes
divergence of the light from the confines of the cross-section of
the waveguide 360 to a desired size (i.e., area). The lens can be
made of any suitable material to perform this function, and various
types of lenses may be used. For example, traditional curved
dielectrics made of glass can de-focus or de-collimate the output
of the waveguide to achieve irradiance over a desired area on the
patient's skin. In another example, so-called "flat" lenses may be
used, such as lenses that incorporate photonic crystals. In such an
embodiment, light from the waveguide can be injected into a flat
slab having photonic crystals that produce a negative index of
refraction and cause the light to be emitted over a broad area. The
injected light can spread over two-dimensional space within the
slab; when applied to the insertion site 350, the slab can blanket
the area with violet light. In yet another example, the dispersion
optic 395 can be a Fresnel lens, which can be flexible to
accommodate being placed on curved surfaces, such as the surface of
a body part.
FIG. 3B shows an alternative arrangement of the system 300 shown in
FIG. 3A, according to one embodiment. Here, the positions of the
dispersion optic 395 and the dressing 320 are switched, i.e., the
dispersion optic 395 is juxtaposed between the catheter 330 and a
portion of the patient's skin 350, and the dressing 320. Compared
to the embodiment shown in FIG. 3A, the arrangement shown in FIG.
3B can reduce or eliminate loss associated with light propagating
through the dressing 320 and can result in increased irradiance to
the target area. In this embodiment, the fiber optic 360 can extend
through the dressing 320 and couple to the dispersion optic 395
using methods known in the optics art fields.
Referring now to FIGS. 3A and 3B, it will be understood that the
type of dressing 320 used in these embodiments can be chosen
according to preference. In a preferred approach, the dressing used
in the embodiment shown in FIG. 3A includes a window capable of
allowing violet light to pass therethrough, i.e., it is
transmissive with respect to violet light; on the other hand, the
dressing used in the embodiment shown in FIG. 3B can be an
occlusive dressing, since its main purpose not to allow light to
propagate therethrough, but instead to protect the underlying skin,
catheter, and dispersion optic.
Referring now to FIG. 4, a system 400 for reducing the likelihood
of infection at or near a catheter insertion site is shown,
according to one embodiment. Here, similar to the embodiments
described above, a catheter 430 is shown inserted into a patient's
arm 460, e.g., subdermally, through an insertion site 450. A light
source 445 capable of producing an effective dose of violet light
447 to cause reduction in proliferation of microorganisms at the
target site is attached to a dressing 420. The dressing 420 is
adhered to the patient's arm 460 through the use of an adhesive
ring 490 disposed about the periphery of the dressing 420. In this
embodiment, the light source 445 includes a power source so that
the unit is self-contained, i.e., it does not require an external
power source to produce the effective dose of violet light. Various
self-contained power sources can be used that will be apparent to
those skilled in the art of light-emitting diodes, for example, and
includes, without limitation, batteries, capacitors, and the
like.
Referring now to FIG. 5, a system 500 for reducing the likelihood
of infection related to catheter insertion is shown, according to
one embodiment. The system 500 includes a light source 510 capable
of producing light in the wavelength range of between about 385 nm
and about 425 nm. Suitable light sources for this purpose include,
without limitation, lasers, diodes, various types of lamps,
excitable filaments, chemi- and electroluminescent materials, and
fluorescent and phosphorescent materials, among others. The light
output of the light source 510 can be directed into a waveguide 540
(e.g., a fiber optic) via one or more coupling optics 570; the type
and configuration of the coupling optics 570 can be chosen
according to the intended use and other factors, and the particular
configuration will be known by those skilled in the art of fiber
optics and light injection.
Referring to FIGS. 5 and 5A, in this embodiment, a portion of a
catheter 543 includes a hollow, flexible sleeve 545 that houses the
waveguide 540 therein; a void space (generally indicated by
reference numeral 546) allows fluid to be transported within the
catheter 543 between the waveguide 540 and the inner surface of the
sleeve 545, between proximal 520 and distal 544 ends. In one
embodiment, a distal end of the catheter 544 can be configured to
receive the light output of the light source 510 in a distal end of
the waveguide 540. The distal end can also include a fluid port 546
for inserting fluid into, or drawing fluid out of the catheter
543.
Referring back to FIG. 5, the catheter can be inserted into a
patient's skin 560 at an insertion site 550 as previously
described. The waveguide 540 can extend from the distal end to a
proximal end 520 where the catheter can be configured to allow
light to be emitted from the waveguide 540 into surrounding tissue
for the purpose of reducing populations of infectious
microorganisms that may be present due to catheterization. In one
embodiment, the catheter 543 can include two sections that can be
reversibly coupled. In such an embodiment, a union 530 allows an
exterior portion of the catheter 543 to be joined to a proximal
portion of the catheter 521 that comes into close proximity to,
and, in some cases, penetrates the patient's dermal layers as shown
in FIG. 5. In such an embodiment, the proximal portion of the
catheter 521 can be configured to emit the light from the waveguide
540 along the length of the proximal portion 521, e.g., through use
of a partially lossy waveguide, or by channeling portions of light
from the central core waveguide 540 to the surface of the catheter
543. In this manner, the proximal portion of the catheter 521 can
irradiate the surface of the patient's skin 560, the dermal layers,
and the surrounding sub-dermal layers (not illustrated in FIG. 5
for clarity) with violet light for the purpose of reducing
populations of infectious microorganisms. It will be understood in
this and other embodiments that catheters of the type described
herein can be inserted into biological lumens, such as a patient's
bladder or gastrointestinal tract, for the purpose of reducing the
likelihood of infection.
In general, the systems and methods described herein can be used to
treat infectious biofilms. As those skilled in the medical arts
will appreciate, biofilms composed of gram-positive or
gram-negative bacteria, yeasts, or other organisms can originate
from the patient's skin, exposure to contaminated medical equipment
or healthcare workers, or other sources, and can be difficult to
treat. In one approach, an infectious biofilm can be treated by
exposing the biofilm to an effective dose of violet light to cause
reduction in the proliferation of the infectious microorganism.
Referring now to FIGS. 6 and 6A, a catheter system 600 is shown.
The catheter system is configured to reduce the likelihood of
infection by delivering an effective dose of violet light to the
surface of skin 602 at, and around the insertion site 610 of the
catheter lumen 603, to reduce or inhibit the proliferation of
infectious microorganisms. In this embodiment, the catheter system
includes a housing 601, which can be flexible or rigid, that
includes a central bore 608 for transporting fluids along the
length of the housing 601. The catheter lumen 603 is a tube that
extends the central bore 608 out of the housing 601 and allows
fluid to flow between the proximal end of the housing 601 and the
patient's blood stream in situations where the system 600 is being
used for IV therapy. It will be understood that the catheter system
600 can be used for other treatments as well (vide supra).
The housing 601 includes one or more waveguides 604a-604d (e.g.,
fiber optics) arranged concentrically about the central bore 608.
It will be understood that the configuration of waveguides and the
central bore shown in FIGS. 6 and 6A is one of many possibilities,
and other arrangements are equally contemplated. The waveguides
604a-604d extend from the proximal end (i.e., nearest to the
patient's skin, as shown) to a distal end of the housing 601. The
distal end of the housing is configured allow distal ends of the
waveguides 604a-604d to receive the output of a light source (not
shown in FIG. 6-6A for clarity) capable of producing an effective
dose of violet light to reduce proliferation of microorganisms near
the incision site 610. The distal end of the housing can also be
configured to allow access to fluids in the central bore 608, so
that fluids can be drawn from, or injected into, the patient.
The proximal end of the housing 601 houses the proximal terminal
ends of the waveguides 604a-604d. In this embodiment, convex
protuberances 606a-606d extend from the housing to produce a lens
effect that causes the light emitted from the waveguide to disperse
across a wider area, although in some embodiments this feature can
be optional. The configuration of the waveguides is such that the
area immediately surrounding the catheter insertion site 610 can be
flooded with violet light. In this embodiment, the application of
intense violet light can be focused near the area where the skin
has been breached for catheterization. As previously described,
this can cause a disruption in the ability of infectious
microorganisms to reproduce, and thus reduce the likelihood of
infection. In some circumstances, the catheter insertion site may
be the area where the blood stream is vulnerable to outside
infectious agents.
Referring now to FIG. 7, a system for reducing the likelihood of
microorganism proliferation is shown. A light source 710 provides
output of an effective dose of violet light (indicated by reference
numeral 714) which can be directed onto a surface 740. The surface
740 can be the surface of living tissue, similar to the embodiments
described herein. In some embodiments, however, the surface can be
non-living, for example, and without limitation, a surface of a
piece of medical equipment, table- and countertops, processing
areas, and other surfaces. In one embodiment, the surface 740 is a
portion of processed food. Examples of processed foods include,
without limitation, meats, such as steaks and other butchery cuts,
eggs, breads, pastas, fish, confectionery items such as cakes and
cookies, vegetables, and other foodstuffs. In another embodiment,
the surface 740 is a portion of packaging used to package foods,
such as a packaging tray for the foods just described.
In general, the system 700 can be used to reduce the likelihood of
microorganism proliferation in and on foodstuffs by irradiating the
target, i.e., the foodstuff or the packaging containing the
foodstuff, with an effective dose of violet light sufficient to
reduce or prevent microorganism reproduction. The system 700 can be
used in, e.g., food processing facilities where foods are processed
prior to distribution. For example, the system 700 can be used as
part of a food processing system where foods are irradiated prior
to packaging so that the proliferation of microorganisms on the
food is reduced. Similarly, the system 700 can be used in food
stores to reduce the likelihood of microorganism growth on
foodstuffs, thereby prolonging the so-called shelf-life of the
food. In one example, foods can be irradiated with an effective
dose of violet light according to a schedule, e.g., every two days,
to reduce microorganism growth.
In general, methods for reducing the likelihood of microorganism
growth on a target surface are provided. Referring now to FIG. 8,
the steps of a method 800 are shown, according to one embodiment.
The method 800 can be used to reduce the likelihood of
microorganism growth on a target surface, and, in some embodiments,
within a host matrix. The method begins at step 801 by identifying
a target. The target can be, in multiple embodiments, skin, tissue,
muscle fiber, and other parts of living systems; one or more
surfaces of medical equipment; one or more surfaces having the
likelihood to become exposed to biological fluids, such as hospital
beds, ambulance patient treatment areas, lavatory areas, etc.;
catheters; food processing equipment; packaged food; and other
surfaces. In a preferred embodiment, the target area is an area of
living tissue immediately adjacent and surrounding a catheter
insertion site, or other area where a body's barrier to infectious
agents has been compromised.
Next, at step 802, the target area is irradiated with an effective
dose of violet light so as to reduce the proliferation of
microorganisms, e.g., infectious microorganisms. As described
heretofore, "violet" light is generally considered to include light
having a center wavelength of between about 385 nm and about 425
nm, e.g., light having a center wavelength of 385 nm, 390 nm, 395
nm, 400 nm, 401 nm, 402 nm, 403 nm, 404 nm, 405 nm, 406 nm, 407 nm,
408 nm, 409 nm, 410 nm, 415 nm, 420 nm, or 425 nm. "Irradiated" and
"irradiating" as used herein, carries the common meaning and
includes exposing the target surface with electromagnetic radiation
from a light source. In general, the intensity of the violet light
can be chosen according to user preference or circumstance to
produce an effective dose sufficient to affect the proliferation of
microorganisms. For example, a high intensity (high flux) can be
used when an active microorganism population is witnessed, i.e., an
infection is present, so as to affect the greatest population of
the microorganisms as possible. Alternatively, a lesser intensity
(lower flux) can be used as a preventive measure to keep lesser
populations of microbes from reproducing and causing infection in a
body.
The decision at step 803 can involve situations where irradiation
is scheduled. "Scheduled irradiation" includes, e.g., irradiating a
target surface on regular or otherwise timed or scheduled
intervals. For example, in some circumstances, patients are given a
catheter that may stay in the body for extended periods of time,
e.g., 3-5 days. During this time, the catheter insertion site can
be exposed to infectious microorganisms, which can increase the
risk of bodily infection. Accordingly, a caregiver can set a timer,
e.g., through an electronic control module, that activates the
light source and causes the target surface to be exposed for a
selected amount of time, at selected intervals. For example, the
caregiver can set the timer to expose a patient's catheter
insertion site for five minutes, every two hours. The intensity of
the exposure can similarly be set and controlled for every exposure
through the control module. If the answer to the "scheduled
exposure?" question in step 803 is "yes," then the method returns
to step 802 to expose the target surface; the loop between step 802
and step 803 iterates until the decision at step 803 is "no." The
method then ends at step 804.
Referring now to FIG. 9, a method 900 for reducing the likelihood
of microorganism growth at or near catheter insertion sites is
shown. This method 900 can be used, without limitation, in a
variety of settings, including hospitals, veterinary clinics,
triage units, emergency rooms, primary care clinics, ambulances,
and in outside areas such as battlefields. This and other methods
described herein can be practiced by, without limitation,
physicians, veterinarians, ambulance crews, EMT's, firefighters,
soldiers, or anyone placing a catheter within a living system.
Beginning at step 901, the catheter insertion site is located,
e.g., on the skin of a patient's arm or hand; while optional, in
preferred embodiments, the site is disinfected to reduce the
population of microbes that may be present, which is a practice
those skilled in the art will recognize.
Next, at step 902, the catheter is inserted into the patient. In
general, but without limitation, this step is often performed by
inserting a needle through the patient's skin and into a blood
vessel, such as in the case of IV therapy. A lumen (hollow,
flexible tube) is then advanced into the blood vessel along the
path defined by the needle; the needle is then withdrawn, leaving
the lumen within the blood vessel. The lumen is generally connected
to other catheter structures and tubing to allow fluids to be drawn
out of, or inserted into, the patient. In some embodiments, such as
the embodiment of FIG. 6, above, a portion of the catheter body
includes one or more waveguides configured to irradiate the
insertion site with violet light from a violet light source.
Next, at step 903, the insertion site is optionally covered to
protect the catheter and the catheter insertion site. In some
embodiments, the catheter and catheter insertion site can be
covered with a dressing having a transparent window to allow
caregivers to monitor the state of the catheter and catheter
insertion site. In preferred embodiments, the dressing includes a
transparent window having a flexible, clear acrylic window, and
adhesive along its periphery allowing the covering to adhere to the
patient's skin. Preferably, the material of the transparent window
is transparent to violet light. Coverings sold under the Tegaderm
brand (vide supra) are preferred.
Next, at step 904, the catheter insertion site and surrounding area
is exposed to an effective dose of violet light to cause reduction
in the proliferation of any microorganisms present. In general, the
intensity of the violet light can be chosen according to
circumstances as described with respect to the method of FIG. 8. In
general, the insertion site can be exposed from a selected vantage
point, e.g., from above, from the side, or in a "blanket" fashion,
if, e.g., the light source is the type as described in FIGS.
3-3B.
Next, decision 905 asks whether the exposure is scheduled on a
repeating basis. In some cases, a caregiver may decide to give the
patient a single dose of radiation; in other cases, e.g., when the
catheter is a "permcath" the caregiver may elect to administer
repeating doses of radiation over a selected period of time. In the
latter case, step 904 is repeated until the number of selected
exposures has been reached.
A number of illustrative embodiments have been described.
Nevertheless, it will be understood that various modifications may
be made without departing from the spirit and scope of the various
embodiments presented herein. For example, the concepts described
herein can be applied toward other scenarios where microorganism
growth and proliferation can be problematic. For example,
microorganism growth is known to cause structural damage to
building components such as wood framework and stucco. To combat
this problem, light sources capable of producing an effective dose
against microorganism reproduction can be placed in areas where
microbes live, or have the capability of colonizing. In one
embodiment, high-intensity LEDs can be placed in the framework of
buildings as they are being constructed; the LEDs can be activated
on a selected schedule (e.g., once a day) to reduce the likelihood
of microorganism growth in areas that would otherwise be accessible
only through demolition.
In one embodiment, the concepts, systems, and methods described
herein can be applied to combating the problem of microorganism
growth inside of fuel tanks, e.g., airliner fuel tanks. It is known
that certain bacteria can degrade aluminum fuel tanks which can be
costly to repair; likewise, it is known that certain bacteria can
degrade fuels such as aviation fuel. Accordingly, light sources
capable of producing an effective dose of violet light to interfere
with microorganism reproduction can be installed in various types
of tanks, e.g., fuel tanks. In such an approach, it can be
advantageous for obvious reasons to use a light source that
produces little heat, such as an LED, or utilize waveguides to
carry violet light from a light source to the interior of the
tank.
In one embodiment, the concepts, systems, and methods described
herein can be used in the restaurant industry to reduce the
likelihood of microorganism growth on cooking and eating
surfaces.
In general, the effective dose of violet light to cause a reduction
in the proliferation of a microorganism can be adjusted for
different types of microorganisms.
Accordingly, other embodiments are within the scope of the
following claims.
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